I just followed this site to install auto-complete on Emacs. I installed it with "M-x load-file RETURN ~/path/to/etc/install.el".
The output of my installation was: http://paste.ubuntu.com/6184523/
After that, I added the recommended code to my ~/.emacs file and restarted Emacs. Typing "M-x auto-complete-mode" says "No match". I also tried to fix it by replacing flet with c-flet etc. but it hasn't changed anything too.
Version: GNU Emacs 24.3.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.8.2)